Javascript object group by day,month,year

Question

I am working on application which I need to do grouping of different sets of javascript object and those will be based on month,day and year.

For day I am doing like

Answer 1

Given a slightly different structure of data:

var data = [{
  "date": "2011-12-02T00:00",
  "value": 1000
}, {
  "date": "2013-03-02T00:00",
  "value": 1000
}, {
  "date": "2013-03-02T00:00",
  "value": 500
}, {
  "date": "2012-12-02T00:00",
  "value": 200
}, {
  "date": "2013-04-02T00:00",
  "value": 200
}, {
  "date": "2013-04-02T00:00",
  "value": 500
}, {
  "date": "2013-03-02T00:00",
  "value": 500
}, {
  "date": "2013-04-12T00:00",
  "value": 1000
}, {
  "date": "2012-11-02T00:00",
  "value": 600
}];

You could use underscore:

var grouped = _.groupBy(data, function(item) {
    return item.date;
});

var groupedByYear = _.groupBy(data, function(item) {
    return item.date.substring(0,4);
});

var groupedByMonth = _.groupBy(data, function(item) {
    return item.date.substring(0,7);
});

console.log(groupedByYear);

See related answer: Javascript - underscorejs map reduce groupby based on date